vitHoward

Rory, I've done blind tests with a modulated signal on a tv and a composite on a monitor and no one could tell the difference. As with everything we do, it takes good equipment with the right cables and correct connectors installed properly to get a professional looking image.

JSimon's idea will work fine if you've got the correct type of coax in place. For modulated signals a good RG6 with 65% FOIL BRAID is perfect. You'll need to calculate your signal loss. RG6 typically looses 6db per 100 ft and each splitter or combiner you use will have a loss (normally marked on the device). A good video signal is just above 0db, around 3 to 7 db is ok. Cameras (composite video) work best on pure copper coaxial, ie; 95% copper shield with a solid copper (not copper covering steel) of at least 20awg. Hope this helps.

kaysadeya, try a plenum cable connector. Plenum cable is usually teflon jacket rather than pvc and is a little bit smaller. FYI for everyone, Connectors Plus in Boynton Beach, Fla www.connectorsplusinc.com has a three piece crimp with both a standard and plenum ferrule in the same package SB-105U They also have the compression connectors and tool. Very nice people to do business with. They are wholesale only so be prepared to prove you're a member of the trade. Tellum Howard sent ya.

My experience is that a twist on cannot be pulled off if installed properly. (I've challege hundreds of people at trade shows to pull one off) The problem is the unrealiability of the center pin connection. For crimps to work well, we need a good quality connector that is designed to fit the guage of the specific wire we are using WITH THE CORRECT DIES for the wire we are using. A generic "one size fits all" crimping tool is unrealiable. My tech's went out yesterday with the new compression connectors. I'll post our results after I get their feedback.

FM Systems makes a device that does what you ask. It takes two composite video and allows them both to pass over a single coax. Obviously, it takes a pair of units to make the magic work

I used to use twist-on's all of the time. I hired two new tech who refused to use them. "They're not for profesionals," they said. Within the next 10 days I had two service calls related to the twist-on. The first the center wire did not seat properly, after removing it I found a perfect "Z" bend. The wire touched the center pin initially, but after time it lost continuity. The other was where the wire was held by the fingers so tight that it actually twisted the wire in two. I've used three piece crimp's ever since. I just got a batch of compression BNC's. They appear very promising. The wire slips in the center pin fingers without twisting. The compression fitting is one piece. A quick squeeze on the compression tool and the fitting tightens on the coax. It appears to have the holding power of a twist on with the integrety of a crimp.

24vac cameras can be line-locked to sync the cameras between switching. 12vdc cameras can't be line-locked. With digital recorders providing time base correction, the sync isn't quite as important as it once was, but if you're doing real time switching, it will get rid of the hiccup between images.

Rory, Your comments just put things in perspective (no pun intended) for me. WOW. CCTVFAN The progressive scan would work IF you could find both a camera and recorder that can work together. Fortunately, the IP cameras (not the cheap web cams) are about to make a major presence in our industry. The cheap ones are getting better and the good one's are getther cheaper. IP cameras not only address the issues of interlaced -vs progressive, but have more scan lines and only require a CAT5 cable instead of coaxial cable. I recently had the opportunity to see a camera that almost does what they pretend to show on TV with the zooming capabilities of recorded video. Stay tuned folks!

Rory, I used to agree with you. I used to do demo's at trade shows on how to properly put on a twist-on connector and challenged everyone to pull it off. No one ever did ....But, I hired a couple of new tech's who refused to use them. They said twist-ons were for amateurs. I bought a good crimper set, reluctantly. Over the next couple of weeks, I went on two service calls where the twist-on's were the problem. The first, the center conducter didn't make it into the center fingers, but bent into a "Z". The other the fingers gripped the conductor so tightly that it actually twisted it and broke it. In both cases, we had a good connection when installed but over time the breaks became apparent when we lost video. I only use twist-on's in emergencies or temporary situations. I've used three piece crimps since but I have to admit the new compression type are looking real good. Howard Kohnstamm http://www.videoguardit.com/cctv_essentials.html

An alternative to using coaxial cable is to use UTP, unshielded twisted pair with baluns. What the balun manufacturer's don't emphasize is that with the unpowered (passive) baluns, the color burst portion of the signal drops off rapidly. If we're going more than a couple of hundred feet to a digital recorder, then we're going to used a powered balun at the headend to insure that we have a good color signal. http://www.videoguardit.com/cctv_essentials.html

One of the most common mistakes that installers make is to use the wrong type of cable and/or connectors. Most people don't realize that the RG59 / RG6 / RG11 markings only refer to the general size and construction of the cable. The foil shielded cable that is normally found at Home Depot, Lowes, etc. is designed for modulated signals, ie: cable TV or Antenna systems where a TV channel is being transmitted. (CATV or MATV) CCTV cameras produce a composite signal which is pure direct current (DC) voltage. The proper cable is a solid copper center with a 95% copper braid. (CCTV) Don't let your installation be "foiled" by using foil shield cable. FYI. RG59 is normally good for 750 to 1000 feet. A cheap self promotion: http://www.videoguardit.com/cctv_essentials.html

Hi folks, The problem with most digital recording is not the recorder, it's the 1940's video standards that we are using. Our NTSC cameras paint a picture of only 525 lines. What we miss is that it's done with 2 passes of 262.5 lines. Since there is a 60th of a second between the first pass and the second pass, we can only record one pass (262 lines). The best DVR (except the new IP type) can only record one pass otherwise it makes any moving object a blur. We are using a big fat crayon to paint a picture with detail. IT CAN'T BE DONE. The solution; 1) place your camera to get the largest target possible. 2) Keep your eyes open for the new IP type systems that use non-interlaced video with more than 525 lines. Howard Kohnstamm, Videoguard Integrated Technologies, Inc. and a cheap plug....http://www.videoguardit.com/cctv_essentials.html

The NICET certification program is moving along. About 5 years ago the CCTV Industry Group of the Security Industry Association created a panel to encourage CCTV installers & designers to get more formal training. They selected NICET as the certifiying body because they are truly indepedent. NICET does not offer training but only provides certification. NICET is nationally recognized and the panel felt that NICET's certification would be an encouragment for both employers and employees to invest in formal education and training. There are many training groups that are in the process of revising their courses to cover all of the elements that are included in the final practice analysis document. As an active member of the SIA subcommittee, I'll be glad to address any questions or comments from interested parties. If I don't know, I'll at least push you in the right direction to get your answer. As an unabashed plug, the link to our website has links to NICET's and the State of Tennessee's related links. Howard Kohnstamm http://www.videoguardit.com/cctv_essentials.html